function [phi, lambda, h] = cart2geo(X, Y, Z, i)
%CART2GEO Conversion of Cartesian coordinates (X,Y,Z) to geographical
%coordinates (phi, lambda, h) on a selected reference ellipsoid.
%
%[phi, lambda, h] = cart2geo(X, Y, Z, i);
%
%   Choices i of Reference Ellipsoid for Geographical Coordinates
%          	  1. International Ellipsoid 1924
%	          2. International Ellipsoid 1967
%	          3. World Geodetic System 1972
%	          4. Geodetic Reference System 1980
%	          5. World Geodetic System 1984

%Kai Borre 10-13-98
%Copyright (c) by Kai Borre
%Revision: 1.0   Date: 1998/10/23
%
% CVS record:
% $Id: cart2geo.m,v 1.1.2.2 2006/08/22 13:45:59 dpl Exp $

% _________________________________________________________________________
%
% Document Change History:
%
% S.No	Date	  Author	Changes
% ----	----     ----------	-----------------------------------------------
% 1.	03/20/07 Sirish 	Added lines 41,47-51 to fix the infinite loop
%                           problem
%
% _________________________________________________________________________
%==========================================================================

if X==0 && Y==0 && Z==0
    phi = NaN;
    lambda = NaN;
    h = NaN;
else
    a = [6378388 6378160 6378135 6378137 6378137];
    f = [1/297 1/298.247 1/298.26 1/298.257222101 1/298.257223563];

    lambda = atan2(Y,X);
    ex2 = (2-f(i))*f(i)/((1-f(i))^2);
    c = a(i)*sqrt(1+ex2);
    phi = atan(Z/((sqrt(X^2+Y^2)*(1-(2-f(i)))*f(i))));

    h = 0.1; oldh = 0;
    iterations = 0;
    while abs(h-oldh) > 1.e-12
        oldh = h;
        N = c/sqrt(1+ex2*cos(phi)^2);
        phi = atan(Z/((sqrt(X^2+Y^2)*(1-(2-f(i))*f(i)*N/(N+h)))));
        h = sqrt(X^2+Y^2)/cos(phi)-N;
        iterations = iterations + 1;
        if iterations > 100
%             fprintf('Failed to approximate h with desired precision. h-oldh: %e.\n', h-oldh);
            break;
        end
    end

    phi = phi*180/pi;
    % b = zeros(1,3);
    % b(1,1) = fix(phi);
    % b(2,1) = fix(rem(phi,b(1,1))*60);
    % b(3,1) = (phi-b(1,1)-b(1,2)/60)*3600;

    lambda = lambda*180/pi;
    % l = zeros(1,3);
    % l(1,1) = fix(lambda);
    % l(2,1) = fix(rem(lambda,l(1,1))*60);
    % l(3,1) = (lambda-l(1,1)-l(1,2)/60)*3600;

    %fprintf('\n     phi =%3.0f %3.0f %8.5f',b(1),b(2),b(3))
    %fprintf('\n  lambda =%3.0f %3.0f %8.5f',l(1),l(2),l(3))
    %fprintf('\n       h =%14.3f\n',h)
    %%%%%%%%%%%%%% end cart2geo.m %%%%%%%%%%%%%%%%%%%
end
